Stoker



Patented Aug. 23, 1938 UNITED STATES PATENT OFFICE STOKER John Goats,Wanwatosa, Wis. Application October 3, 1936, Serial No. 103,8801i 11Claims. (01. 198-64) My present invention relates generally toimprovements in the art of feeding pulverulent fuel into combustionchambers, and relates more specifically to improvements in stokers fordelivering.

regulated quantities of coal or the like to furnaces or boilers.

Generally defined, an object of my present invention is to provide animproved stoker which is simple, compact and durable in construction,and

m which is moreover highly efllcient in use.

Many types of stokers have heretofore been proposed andplaced upon themarket, but all of these prior devices are relatively objectionableeither because of their unsightly appearance, or

II due to the inconvenience encountered in supplying fuel to the hopper,or on account of the inefiiciency of the mechanical feed structure, orbecause of the escaping dust and fumes. Since stokers are rapidlybecoming more popular for 90 residential use, it is important thatsuchdevices present an attractive appearance and that they be readilyaccessible for the delivery of fuel thereto at least to the same extentas the furnace or boiler firing door was accessible. It is also 25desirable that these mechanical stokers be dependable in operation, andfoolproof against excessive damage in case the feed mechanism becomesobstructed by tramp iron or other abnormal objects which may frequentlyappear in low 30 grade fuel such as is ordinarily supplied to a stoker.It is moreover desirable to have the stoker bin and other casingseffectively sealed against possible escape of gases and dust, and noneof the prior commercial fuel stokers have 35 embodied all of theseimportant and desirable features. i 7 It is therefore anmore specificobject of .the present invention to provide an improved stoker assemblywhich obviates all of the objectionable 40 features or the prior devicesof this type, and which is dependable in operation in that the fuelsupply is automatically and positively delivered from the hopper to thegrate.

5 Another specific object of my present invention is the provision of astoker unit which is extremely attractive in appearance, and whereinthe. fuel may be most conveniently supplied to a hopper which is adaptedto be set for loading from the 5 rear of the unit or from either sidethereof.

A further sp ific object of this invention is to provide an improvedhopper and feed screw assemblage wherein the fuel is effectivelydelivered by gravity to the zone of action of the screw,

55 and the latter is adapted to most efiectively withdraw the descendingfuel charge from the bottom of the hopper.

Still another specific object ofmy present invention is the provision ofimproved instrumentalities for positively preventing choking of the fuelfeed ducts of a stoker, and for protecting the apparatus againstexcessive damage due to abnormal conditions of operation.

An additional specific object of the invention is to provide improvedclosures for a stoker supply. m bin or hopper, which while permittingready access to all portions of the normally concealed storage space andfeed mechanism, will also effectively guard against possible escape ofgases, soot and dust.

My present invention also contemplates provision of an improved stokerunit which can be manufactured and sold at moderate cost, which may bequickly installed, and which is extremely economical in normaloperation.

The above as well as other specific objects and advantages of thisinvention will be apparent from the following detailed description.

A clear conception of embodiments of the several features constitutingthe present invention, and of the mode of constructing and of operatingstoker units embodying these features, may be had by referring to thedrawing accompanying and forming a part of this specification, whereinlike reference characters designate the same or similar parts in thevarious views:

Fig. 1 is a combined rear and side perspective view of a complete stokerunit especially adapted for industrial or residential service;

Fig. 2 is an enlarged central vertical l'ongitudinal section through thefuel supply structure, showing the improvedhopperpositioned for loadingfrom the rear; t

Fig. 3 is a similarly enlarged central vertical transverse sectionthrough the lower portion of 40 the improved fuel supply assemblage; and

Fig. 4 is a somewhat diagrammatic top view of thehopper assemblage,showing the hopper in solid lines positioned for rear loading, and indotand-dash lines positioned for alternative side loading.

While my invention has been illustrated and described herein as beingspecifically applied to a relatively small stoker unit for coalespecially adapted for domestic service, it is not the intent to therebyunnecessarily restrict the scope, since some of the improved featuresmay obviously be more generally applied.

Referring especially to Fig. 1 of the drawing,

the improved stoker unit shown therein comprises in general a grateassemblage 8 which is normally disposed beneath the combustion chamberof a furnace or boiler; a fan or blower Ill rotatable by means of anelectric motor 9 to deliver air to the combustion chamber through thegrate assembly 8; a hopper II for receiving the fuel supply through adoor l2 and having an upwardly open cup-shaped supporting base IS; anormally concealed feed screw H for delivering fuel forwardly from thehopper i I to the grate assembly through a tubular casing I5; and a gearbox IE forming a housing for transmission gearing adapted to transmitrotary motion from the motor 9 to the fuel feed screw H in a well knownmanner.

The hopper H which is preferably formed of sheet metal, is of improvedconstruction as shown in Figs. 2, 3 and 4, and comprises a downwardlydirected substantially upright portion I I, the lower end of which isdisposed within and is in open communication with the interior of thecupshaped base l3; and an upwardly laterally directed and curved portioni8 of gradually diminishing cross sectional area terminating in a fuelsupply opening disposed beyond the adjacent side wall of the hopper andwith which the door I! ooacts. The lower portion of this hopper H is ofequilateral polygonal cross-sectional shape, substantially square asshown in Fig. 4, and the confining wall for the lower hopper end is oflike shape so that the hopper l I may be interchangeably positioned withits upper inlet opening either rearwardly accessible as shown in solidlines in 8. 4, or accessible from either side of the stoker as indicatedin dot-and-dash lines. When the hopper II has been applied to the baselit in the desired position, it may be riveted, welded or bolted to thebase so as to rigidly interconnect these parts.

The rectangular peripheral frame is of the lateral upper inlet opening,is preferably located outwardly beyond the adjacent hopper side wall andlies in a plane which is slightly inclined toward the hopper axis asshown in Figs. 1 and 2, and the fuel supply opening is preferablydisposed above the floor line at a height substantially equal to that ofa standard furnace or boiler firing, open- 'ing. The inlet closure doorI 2 is swingably suspended by means of hinges i9 from one side of theframe l9 and has a continuous seal formed of flexible material such asrubber, which is adapted to be forced into sealing contact with theframe ridge 2| with the aid of a latch 22, see Fig. 2. The latch 22 andthe door l2 are manipulable by means of a handle 23, and it will benoted that when the door I! is located rearwardly over the motor 0 asillustrated in Fig. 1, the exposed portion of the stoker assemblage hasan attractive and compact streamlined appearance.

The improved cup-shaped hopper base l3 may be formed in any suitablemanner and has oppositely inclined side walls 24 connected at theirlower ends with a flat bottom which extends beneath the fuel feed screwit as shown in Figs. 2 and 3, thereby exposing both the top and bothsides of the screw I to the fuel descending from the hopper l I upon thebase. One or both of the inclined side walls 24 may be provided with anopening which is normally closed by means of a readily removable closureplate 25 coacting with guide lugs 26 as shown in Figs. 1 and 3, and thebase I 3 may also be provided with suitable supports 21. The tubularcasing l5 within which the 1 screw II is rotatable, may be formed insections one of which is formed integral with the base It as indicatedin Figs. 2 and 4 and has an upper opening therein extending from theforward lower wall of the hopper ll along the top of the screw M. Thisupper opening is normally sealed by a special closure plate 28 shown indetail in Figs. 2 and 4, this plate having a rearwardly extendingportion 29 projecting along the screw beneath the hopper wall andnormally being held in position by cap screws 30. The rear end of theplate 28 has its edge disposed at an angle conforming substantially withthe pitch of the screw l4, and the medial lower face 3| of the plate hasa sloping shape so that when the cap screws 30 are removed or broken,the plate 29 will be automatically forced forwardly by the screw I 4 andwill be simultaneously lifted out of the opening to expose the adjacentportion of the feed screw.

While the hopper H is formed downwardly diverging or enlarging in crosssection in order to prevent bridging of the fuel over the conveyingscrew I4, I may additionally provide automatic bridging preventingmechanism such as disclosed in detail in Figs. 2 and 3. This improvedmechanism comprises a central disk or wheel 32 supported for freerotation within the center of the lower hopper portion I"! by ahorizontal shaft 33 which spans the hopper. The disk wheel 32 has aperipheral series of abutments 34 which are successively engageable withthe constantly advancing forward face of the feed screw It, tocontinuously revolve the wheel; and also has laterally projectingcutters or spurs 35 extending in opposite directions therefrom. It willbe apparent that as the screw I4 is rotated, the spurs 35 will berevolved within the lower hopper portion l1 and will positively preventbridging of fuel within the hopper I I over the feed screw H. The fuelfeed screw i4 is of well known construction, preferably having differentpitch as it approaches the grate assembly 8, and is adapted to be drivenat variable speeds through speed change gearing of usual and well knownconstruction confined within the gear box l6.

During normal operation of the improved stoker unit, the motor 9 isoperable to actuate the blower i0 and to thereby supply air to the grateassembly 8, and is simultaneously functioning to rotate the fuel feedscrew l4, whenever the motor is placed in operation. The hopper Ii maybe charged with bulk 'fuel when the door I 2 is opened, and the lateralinlet opening of the hopper ll obviously enables original disposition ofthis door l2 so as to permit most convenient loading of the hopper fromthe fuel supply bin. The fuel admitted to the hopper ll descends towardthe cup-shaped base II and settles or slides along the inclined sidewalls 24 toward the exposed sides of the rotating screw ll. As the screwit rotates, the disk wheel 32 is simultaneously revolved about the axisof its supporting shaft 33, thereby causing the spurs 35 to travelthrough the mass of fuel within the lower portion of the hopper II andto prevent packing or bridging thereof. The fuel bed is thus caused tomove downwardly and inwardly toward the screw ll both from the top andsides, and this action enables the feed screw to constantly withdraw afull charge of fuel from the hopper so long as the latter is properlysupplied. This operation of the fuel feeder is obviously entirelyautomatic and requires no attention except the maintenance of asufficient supply of fuel to the hopper.

In case the admitted fuel contains a large piece of tramp iron or someother hard object which cannot be broken and fed by the screw H, theobject might damage the screw or casing if no prounit may bemanufactured, installed and operated ing at one side thereof vision weremade to prevent such damage. Such an object will be fed by the screw lltoward the conveyor tube or casing I5, and upon striking the inwardlyprojecting-portion 29 ofthe plate 28;will ultimately produce sufficientpressure to break the cap screws 30. After these clamping screws arebroken, the plate 28 will be pushed along the casing l and will belifted clear of the adjacent opening, by the lower inclined surface 3|.The

obstructive hard object will subsequently escape through the upperopening in the casing l5, and the closure plate 28 may thereafter bereapplied to the opening with new cap screws 30. I

The interiors of the hopper II and screw casing I! besides being freelyaccessible through the door I! and past the plate 28, are alsoaccessible upon removal ofthe side closure plate 25. All portions of thefuelvfeed assemblage are thus conveniently accessible for inspection andrepairs, and the mechanism is effectively protected against seriousdamage. Since the fuel supply door I2 is disposed similar to an ordinaryfiring door, the hopper H may be readily loaded, and the formation ofthe hopper with a symmetrical polygonal lower end which isinterchangeably cooperable with the base l3 in different angularpositions, permits location of the door at the most convenient place ofaccess.

From the foregoing description it will be apparent that the presentinvention provides a stoker assembly which is highly dependable andautomatic in operation when properly supplied with fuel, and which maybe conveniently loaded. The unit besides being readily accessible, iscompact and very attractive in appearance, and is also extremely durablein construction. The fuel is most eifectivcly delivered to the feedscrew by the inclined base walls and stirring device cooperating withthe hopper formation, thus insuring most eifective delivery of fuel tothe grate. The apparatus is moreover protected against serious damage,and is also well guarded against possible escape of gases, soot anddust. The improved stoker at moderate cost and has proven highlyefficient in actual commercial operation.

It should be understood that it is not desired to limit the invention tothe exact details of construction, and to the precise mode of operationherein shown and described, for various modifications within the scopeof the appended claims may occur to persons skilled in the art.

I claim:-

1. In a stoker, feed mechanism for delivering fuel to a place ofutilization, a hopper for delivering fuel to said feed mechanism andhaving '9. lat-.

erally directed upper wall and a fuel inlet openmeans forinterchangeably positioning said hopper to permit injection of fuelthrough said inlet opening either longitudinally or laterally of thedirection of fuel delivery from said hopper by said mechanism.

2. In a stoker, a feed screw for delivering fuel to a place ofutilization, a hopper having a downwardly extending lower portion fordepositing fuel into the zone of action of said screw and alsohaving alaterally directed upper wall and a fuel inlet opening near the top andat one side thereof beneath said wallfand means for interchangeablysupporting said hopper to permit injection of fuel throughsaid openingindifferent directions.

3. In a stoker, fuel feed mechanism, a hopper for delivering'fuel tosaid mechanism and comprising a downwardly directed lower portion andbeneath said wall, .and

a laterally curved upper portion terminating in a.

substantially horizontally directed inlet opening at the upper end andat one sideof the hopper, and a laterally opening closure door for saidinlet opening.

4. In a stoker, fuel feed mechanism, a hopper for delivering fuel tosaidmechanism and comprising a downwardly directed lower portion and alaterally curved upper portion terminating in a substantiallyhorizontally directed inlet opening at the upper. end thereof,. alaterally opening closure door for said inlet opening, and a support forsaid hopper formed to permit interchangeable positioning of said door indifferent locations.

5. In a stoker, a fuel feed screw, a base having fuel supportingsurfaces inclined at slight angles laterally toward and a substantiallyhorizontal surface connecting the adjacent ends of said inclinedsurfaces and extending beneath said screw, a hopper supported by saidbase and having a downwardly directed lower portion and a laterallydirected converging upper portion provided at itsend with a laterallydirected side inlet opening, and a laterally swingable closure door forsaid opening.

6. In a stoker, a fuel feed screw, a base having fuel supportingsurfaces inclined at slight angles laterally toward and extendinghorizontally beneath said screw, ,a hopper supported by said base andhaving a downwardly directed lower portion and a laterally directedconverging upper portion provided at its end with a laterally directedside inlet opening, a laterally swingable closure door for said opening,and means for securing said lower hopper portion to said base indifferent fixed positions.

'7. In a stoker, a fuel feed screw, a base having:

fuel supporting surfaces inclined at slight angles laterally toward andextending horizontally beneath said screw, a hopper supported by saidbase and having a downwardly directed lower portion and a laterallydirected converging upper portion provided at its end beyond the side ofthe hopper with a laterally directed side inlet opening, and a laterallyswingable closure door for said opening, the supporting end of saidlower hopper portion and the hopper receiving portion of said basehaving equilaterally polygonal similar transverse cross-sections.

8. In astoker, a fuel feed screw, a shallow wide base extendinghorizontally beneath said screw and laterally beyond the opposite sidesthereof, the top and both entire sides of said screw being open to theinterior of said base, and

a hopper having a vertically directed lower portion in opencommunication with said base interior and also having an upper laterallycurved portion prpvided'at its end with a laterally directed side inletopening located outwardly beyond the adjacent side wall of said verticalportion.

9. In a stoker, a fuel feeder, a sheet metal hopper having a downwardlydirected lower portion for directing fuel in bulk toward said feeder andalso havingv an integral laterally directed upper inlet portion providedwith a substantially horizontally directed side inlet opening having aninclined bounding edge, and a laterally swingable door having a flexiblecontinuous seal cooperable with said edge.

10. In a stoker, a fuel feeder, a hopper having a substantially verticallower portion for directing fuel by gravity toward said feeder and alsohaving a laterally directed upper inlet portion provided with asubstantiallyhorizontally directed side inlet openim havingsubstantially upright side bounding edges connected by horizontal upperand lower-bounding edges, the upper and lower bounding walls of saidhopper at said opening being gradually downwardly curved receding fromthe opening, and a laterally swingable door having a continuous flexiblesealing strip cooperable with said opening edges.

11. Ina stoker, a. fuel feeder, a. hopper having an upright lowerportion for directing fuel toward said feeder and also having alaterally directed upper portion provided with curved upper and lowerbounding walls merging into said lower portion and with a substantiallyhorizontally directed inlet opening at the ends of said walls beyond aside of said lower portion, and a. laterally swingable door for sealingsaid inlet opening.

JOHN GOE'IZ.

